1. Technical Field
The present disclosure relates to a video display system, a video display device, and a video display method for displaying video data that is captured from directions in the entire celestial sphere.
2. Description of the Related Art
A camera (hereinafter, referred to as an omnidirectional camera) that can capture a video image from directions in the entire celestial sphere (that is, in the 360-degree range) has started to emerge in recent years. Since the omnidirectional camera can capture a wide range video image, capturing is mostly performed in an outdoor environment considering the assumed use thereof. In the outdoor environment, however, a video image captured in the same direction as sunlight and a video image captured in the opposite direction to sunlight coexist in a 360-degree range video image, and the luminosity of the captured video image is rendered non-uniform according to an azimuth. Thus, an approach to increase the dynamic range of a camera that captures a video image in the opposite direction to sunlight (that is, a video image having a low luminosity) is taken into consideration.
In order to effectively use the dynamic range of the camera upon capturing an image, Japanese Patent Unexamined Publication No. 7-294876, for example, is known as a preceding technology for displaying an image captured by the camera in a separate display device (for example, a head mounted type display).
In the display device disclosed in Japanese Patent Unexamined Publication No. 7-294876, usually, a plurality of displays of liquid crystal displays (LCDs) is irradiated by a main backlight. An image signal upon capturing and a measured light information signal are input into a controller of the display device. The controller performs control of each drive circuit based on the measured light information to drive a plurality of auxiliary backlights, a plurality of auxiliary flashes and a plurality of auxiliary lamps to emit light, and the plurality of LCDs is irradiated in an auxiliary manner. Accordingly, a sense of realism produced by a change in the luminosity of a photogenic subject upon capturing is not damaged.
There is known a stereo camera that includes two capturers fixed in one casing in such a manner to capture the same photogenic subject by using left and right capturers. The stereo camera captures a photogenic subject from a plurality of different directions and records planar direction information and depth direction information (three-dimensional information).
However, in a case where a user sees the video image captured by the omnidirectional camera using the head mounted type display (for example, a head mounted display; HMD), the video image is not clearly displayed even if a dark video image such as a video image captured in the opposite direction to sunlight is illuminated by a backlight.
In a case, for example, where the user wearing the head mounted display sees the video image captured by the omnidirectional camera, the head mounted display, in accordance with a motion of the user, displays the video image by switching between various directions of the directions in the entire celestial sphere in a short amount of time. Thus, if the luminosity of the video image is different according to a direction in which the user watches, illuminating the video image uniformly at the same luminosity does not improve the visibility of the video image.